If you wanted to know the average number of children for men and
women over 30 in 1982 you could use a perl program like this:

while( <> ) # go through all line in file
{
next unless /^1982/; # gets rid of other years
($yr,$sex,$age,$kids) = split; # break up the line into pieces
next unless $age > 30; # skip younger people
$parents{$sex}++; # Add one to parent tally by sex
$totkids{$sex} += $kids # Add kids to total by parent sex
}
$avg_dads = $totkids{"M"}/$parents{"M"}; # figure out average for M
$avg_moms = $totkids{"F"}/$parents{"F"}; # figure out average for F
print "Average for moms: $avg_moms\n";
print "Average for dads: $avg_dads\n";<

You would put this program in file, say "countem.p", and then execute it
like so:

perl countem.p data_set_name_here

Ok, this example is contrived and the program seems very arcane
with all those $'s. Also, perl certainly isn't a substitute for
more sophisticated statistical packages.

However, notice the benefits of using perl: (1) the dataset need
not be converted to SAS, TSP or any other format; (2) it would
be easy to change the cutoff age or other details (find average
age of people with more than 2 kids, etc.); (3) there are none
of the number/character/formatting/initialization hassles there
would be if you tried to use an ordinary programming language
like C or Fortran.
c
Perl is also very good for managing files and other things that
statistical packages can't do at all and that programming languages
can do, but only with a lot more work.

There is an excellent book available which explains all about perl:
"Programming Perl" by Larry Wall (the author of perl) and someone else.
It is published by O'Reilly and Associates and is carried by the Co-op
in their computer trade section. The manual page ("man perl") is
comprehensive but less convenient.